1. Field of the Invention
This invention relates to the field of nerve stimulators and locators of the type which apply an electric current to a nerve in order to obtain a response which locaties the nerve for a physician prior to the injection of an anesthetic or neurolytic agent for the purpose of blocking the nerve and, more particularly, to such a device which can be clamped onto, and completely supported by, a conventional syringe.
2. Description of the Prior Art
It is common practice for an anesthesiologist to attach a nerve stimulator to either an insulated an uninsulated injection needle during the performance of regional anesthesia. When the tip of the needle approaches the nerve, a pulsed electrical current discharge will depolarize the motor or sensory nerve and cause a twitch of the inervated muscles, or paresthesias should a sensory nerve be involved. By using this technique, the anesthesiologist can use a minimum amount of local anesthetic solution to obtain a satisfactory nerve blockade. A detailed description of this technique appears in Raj et al, "Use of the Nerve Stimulator for Peripheral Blocks", Regional Anesthesia, April-June 1980, pages 14-21. Even though the stimulator device is electrically connected to the injection needle, the stimulator device, itself, is separate from the injection needle and requires operation by an assistant who must be in verbal contact with the physician who is inserting the needle for the purpose of stimulating and locating the nerve and then, subsequently, blocking the nerve by injecting an anesthetic solution.
Similarly, U.S. Pat. No. 3,682,162 discloses the combination of an hypodermic needle and a nerve stimulator, but again this stimulator is separate from the hypodermic needle and requires operation by someone other than the physician who is injecting the needle; furthermore, the needle has a special electrode construction.
U.S. Pat. No. 3,078,850 discloses an electrochemotherapeutic cardiac device in which an electric pulse source is electrically connected to an injection needle, but, again, the pulse source is separated from the needle and must be operated by an assistant while the physician is using the needle.
U.S. Pat. No. 3,830,226 discloses an electrically powered nerve stimulator, but it is not intended to be used in physical combination with a syringe and injection needle.
U.S. Pat. No. 4,164,214 discloses an electrical probe for stimulating the nerve in the dental pulp of teeth, but it is not used in combination with an injection needle.